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Extremely critical Ruby on Rails bug threatens more than 200,000 sites

"It is quite bad," Murphy told Ars. "An attack can send a request to any Ruby on Rails sever and then execute arbitrary commands. Even though it's complex, it's reliable, so it will work 100 percent of the time."

via @arstechnica — http://arstechnica.com/security/2013/01/extremely-crtical-ruby-on-rails-bug-threatens-more-